1. Field of the Invention
The present invention relates to an antiglare film, a manufacturing method thereof, and a transmission type liquid crystal display. In particular, the invention relates to an antiglare film that can be provided on the surface of a window or a display such as a liquid crystal display (LCD), a CRT display, an organic electroluminescence display (ELD), a plasma display (PDP), a surface emission display (SED), and a field emission display (FED).
2. Description of the Related Art
In the field of displays such as liquid crystal displays, CRT displays, EL displays, and plasma displays, an antiglare film having a concave-convex structure on the surface is known to be provided on the display surface in order to prevent the decrease in visibility caused by reflection of external light on the display surface during viewing.
For example, a method for forming a concave-convex structure on the surface of an antiglare film by emboss processing and a method of forming a concave-convex structure on the surface of an antiglare film by coating a coating liquid in which particles are admixed to a material forming a binder matrix and dispersing the particles in the binder matrix are known as methods for forming an antiglare film having a concave-convex structure on the surface. In the antiglare film in which a concave-convex structure formed by such methods is provided on the surface, the external light falling on the antiglare film is scattered by the concave-convex structure of the surface, the image of external light becomes blurred, and the decrease in visibility caused by reflection of external light on the display surface can be prevented.
JP-A-6-18706 discloses antiglare films of various forms in which particles are dispersed in a binder matrix. The antiglare films using the binder matrix and particles described in JP-A-6-18706 can be manufactured by a process including fewer steps than that using the above-described embossing and, therefore, the antiglare films can be produced at a lower cost.
A variety of techniques used to obtain antiglare films using a binder matrix and particles have been disclosed. For example, JP-A-2003-260748 discloses using a combination of a binder matrix resin, spherical particles, and irregular shape particles. JP-A-2004-004777 discloses using a binder matrix resin and particles of a plurality of different diameters. JP-A-2003-004903 discloses providing surface concavities and convexities and specifying the cross-sectional area of concavities.
JP-A-11-305010 discloses using internal scattering together with surface scattering, setting the internal haze value (cloudiness) of the antiglare layer to 1%-15% and setting the surface haze value (cloudiness) to 7%-30%. JP-A-2002-207109 discloses using a binder resin and particles with a diameter of 0.5 μm to 5 μm, setting the difference in refractive index between the binder resin and the particles to 0.02-0.2, and setting the compounding ratio of the particles to more than 10 parts by weight and less than 30 parts by weight per 100 parts by weight of the binder resin. JP-A-2000-338310 discloses using a binder resin and particles with a diameter of 1 μm to 5 μm, setting the difference in refractive index between the binder resin and the particles to 0.05-0.15, using an appropriate solvent, and setting the surface roughness within a predetermined range. JP-A-2000-180611 discloses using a binder resin and a plurality of particles and setting the difference in refractive index between the binder resin and the particles to 0.03-0.2. JP-A-11-160505 discloses setting the surface haze (cloudiness) to a value equal to or greater than 3 and setting the difference between a haze value in the normal direction and a haze value in the direction at ±60° to a value of equal to or less than 4.
Antiglare films of various configurations developed to attain a variety of objects have thus been disclosed. Performance of antiglare films used on the front surface of display differs between the displays. In other words, an optimum antiglare film differs depending on the resolution and object of use of the display. Therefore, antiglare films of various types corresponding to a variety of objects are needed.
Antiglare films are provided on the surface of displays of notebook personal computers, desktop personal computers, and TV monitors. In recent years, antiglare films with a low haze value and inhibited antiglare ability have been used with the object of increasing contrast. The resultant problem is that reflection is increased and image recognizability is decreased. Accordingly, it has been suggested to laminate an antireflection layer on the antiglare layer. However, the problem arising when an antireflection layer is laminated on the antiglare layer is that material cost and number of processes are increased and cost is raised, while the production yield is degraded.